Apical periodontitis (AP) has traditionally been viewed as a localised dental condition – an inflammatory response to microbial invasion of the root canal system. However, emerging longitudinal research is reshaping this perception, revealing AP as a chronic oral disease with systemic implications. From cardiovascular risk to metabolic imbalance, the evidence is clear: AP is more than a tooth problem – it’s a public health concern.
Figure: Apical Periodontitis – A Local Infection with Systemic Impact
Microbial Complexity and Clinical Relevance
At the core of AP lies a diverse and resilient microbial ecosystem. Advances in next-generation sequencing have identified key bacterial genera in failed root canal treatments, with Enterococcus frequently dominating. Known for its survival in harsh environments, Enterococcus is strongly associated with persistent infections. Other notable genera include Streptococcus, Prevotella, Actinomyces, and Cutibacterium – the latter often found in abscessed and refractory lesions1,2.
Symptomatic AP cases tend to exhibit greater microbial diversity, suggesting a link between microbial richness and clinical presentation. The presence of opportunistic pathogens like Cutibacterium acnes in both symptomatic and asymptomatic cases, which have also been regarded as nosocomial pathogens, highlights the need for rigorous cross-infection control protocols during endodontic procedures 1-3.
Bacteremia Without Intervention
Traditionally, bacteremia has been associated with invasive dental procedures. Yet, recent studies suggest that AP itself may act as a reservoir for bacteremia – even before any clinical intervention. In one longitudinal study, bacterial DNA was detected in the blood of AP patients prior to treatment, with overlapping taxa found in both blood and root canal samples4.
This microbial crossover points to a direct pathway from oral infection to systemic circulation. Particularly concerning is the detection of Streptococcus species linked to infective endocarditis, underscoring the cardiovascular risks of untreated AP4.
Systemic Inflammation and Metabolic Disruption
AP doesn’t just harbour bacteria – it drives systemic inflammation. Patients with untreated AP show elevated levels of inflammatory biomarkers such as interleukin-1β (IL-1β), high-sensitivity C-reactive protein (hs-CRP), fibroblast growth factor-23 (FGF-23), and asymmetric dimethylarginine (ADMA) – all closely associated with cardiovascular disease (CVD) risk5,6.
Moreover, AP appears to influence metabolic health. Even in otherwise healthy individuals, AP has been linked to elevated HbA1c, triglycerides, LDL cholesterol, and body mass index (BMI)6. Metabolomic profiling reveals disrupted glucose and lipid metabolism, insulin resistance, and tryptophan depletion – further reinforcing AP’s systemic impact.
Endodontic Treatment: A Path to Systemic Wellness
The good news is that successful endodontic treatment can reverse many of these systemic effects. Longitudinal data show significant reductions in inflammatory biomarkers and improvements in metabolic indicators following root canal retreatment or periapical surgery5,6. These outcomes suggest that endodontic therapy may hold prognostic value beyond oral health.
The British Endodontic Society (BES) is committed to furthering the dental health and wellbeing of the nation through pioneering, researching, and supporting members to provide the best possible standards of care to their patients. It’s focus on public health and the importance of high-quality endodontic treatment is reflected in the wide range of awards and prizes the BES offers its members in recognition of their successes.
A Call for Integrated Care
Apical periodontitis is not just a dental issue – it’s a systemic one. Its association with inflammation, metabolic imbalance, and non-communicable diseases (NCDs) positions AP as a critical intersection in oral-systemic health. Dental professionals must recognise this broader impact and advocate for timely diagnosis and management. Integrating endodontic care into preventive health strategies can improve outcomes far beyond the dental chair.
It’s time to move beyond the root and embrace a more holistic approach to dental care.
For more information about the BES, or to join, please visit the website www.britishendodonticsociety.org.uk or call 07762945847
Dr Sadia Niazi
[BDS, MSc, PhD, M.Endo RCS (Eng), M Endo (RCSEd), F (Endo) RCSEd, Specialist list in Endodontics, FHEA]
Dr Sadia Niazi is a Senior Clinical Lecturer and Honorary NHS Consultant in Endodontology at King’s College London. She leads research on oral microbiome–host interactions and systemic disease links, with multiple funded projects and international collaborations. A recipient of the British Endodontic Society’s Inspirational Lecturer Award, she also leads undergraduate endodontics at King’s. Her work has shaped infection control protocols and advanced understanding of apical periodontitis as a systemic health concern.
References:
1 Bakhsh, A. et al. Apical periodontitis microbiome association with salivary and serum inflammatory burden. Int Endod J 58, 504-515 (2025). https://doi.org:10.1111/iej.14184
2 Niazi, S. A. et al. Propionibacterium acnes and Staphylococcus epidermidis isolated from refractory endodontic lesions are opportunistic pathogens. J Clin Microbiol 48, 3859-3869 (2010). https://doi.org:10.1128/JCM.01326-10
3 Niazi, S. A., Vincer, L. & Mannocci, F. Glove Contamination during Endodontic Treatment Is One of the Sources of Nosocomial Endodontic Propionibacterium acnes Infections. J Endod 42, 1202-1211 (2016). https://doi.org:10.1016/j.joen.2016.05.016
4 Bakhsh, A., Moyes, D., Mannocci, F., Proctor, G. & Niazi, S. Links between Nosocomial Endodontic Infections and Bacteremia Associated with Apical Periodontitis and Endodontic Treatment. J Endod 51, 140-149 (2025). https://doi.org:10.1016/j.joen.2024.11.009
5 Bakhsh, A., Moyes, D., Proctor, G., Mannocci, F. & Niazi, S. A. The impact of apical periodontitis, non-surgical root canal retreatment and periapical surgery on serum inflammatory biomarkers. Int Endod J 55, 923-937 (2022). https://doi.org:10.1111/iej.13786
6 Al-Abdulla, N. et al. Successful endodontic treatment reduces serum levels of cardiovascular disease risk biomarkers-high-sensitivity C-reactive protein, asymmetric dimethylarginine, and matrix metalloprotease-2. Int Endod J 56, 1499-1516 (2023). https://doi.org:10.1111/iej.13979
